Have you ever wandered across a tree missing a ring of bark and wondered what was creating the ring and why? I too had these questions and they remained unanswered until I began performing the task as an Oakland Township Natural Areas Stewardship Technician. I learned that removing a complete ring of bark around a tree stem is called girdling, and it is used in Oakland Township’s natural areas to selectively phase out invasive trees by stripping off their nutrient pathways.
As deforestation awareness and efforts to plant trees continue to increase, girdling may register as counterintuitive. However, we girdle specific trees, and only in areas we are restoring to historic oak savanna or prairie communities. Lost Lake Nature Park, Paint Creek Heritage Area – Wet Prairie, and Bear Creek Nature Park contain these historic communities so we are focusing our girdling and restoration efforts this summer in these natural areas.
Although red maple and basswood are native to Michigan, they are quite damaging to the historic oak communities. These trees grow so abundantly that their dense stands take up the real estate, nutrients, and light that fire-dependent, light-loving understory plants require. In the dense shade under red maple it is very rare to find any young oak trees. At Lost Lake Nature Park red maples outnumbered the old growth oak trees 12:1!
In Oakland Township’s natural areas we use a low-cost, low-impact girdling tool composed of a metal handle and arched blade to strip the trees bark, phloem (sugar transport highway) and vascular cambium (cells that produce phloem and xylem) from the trunk. This tool is quite simple and easy to use, but you can also girdle with chainsaws and hatchets if you don’t have a special girdling tool.
As the girdled trees defoliate and phase out, the sun’s rays reach plants like poke milkweed, harebell and whorled loosestrife, providing the essential energy to thrive. Many other oak savanna and prairie specialist plants are either lying dormant in the soil as seeds, or holding out as small plants until the ideal light conditions are created. For example: hoary puccoon, a rare and high quality plant began to flower at Paint Creek Heritage Area – Wet Prairie when the canopy was thinned! Furthermore, there’s an abundance of small huckleberry and blueberry at Lost Lake Nature Park patiently waiting for an opened tree canopy to reach their full potential. I am very excited to revisit the areas we girdled in a couple years to see what new plants are claiming space in these beautiful communities.
Opening up the tree canopy and conducting occasional prescribed burns are important practices of Oakland Township’s restoration efforts, helping to reinvigorate our diverse and tightly knit natural communities. The landscape of southeast Michigan was maintained by the Anishinaabe people for thousands of years. This culturally related group of indigenous people inhabited much of the Great Lakes region and lived with the land through with a deep relationship and knowledge of its beautiful natural communities. Through cultural practices like prescribed burns and sustainable harvesting, the Anishinaabe maintained these unique oak communities. Now, after more than 200 years of degradation, we are doing our best to restore them and acknowledge the original stewards of the land.
3 thoughts on “Thinning Trees to Preserve and Restore Oak Woodland and Savanna Habitat”
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Max, you did another great job of explaining a difficult subject. Thanks for taking it on. And I love your flower photos! Good luck when you’re back at school this year. Hope we see you again before too long.